1099 Income Taxed at 46 Percent?

I worked part of 2015 as an independent contractor. My 1099-MISC shows ~$28k and my W-2 wages are about $70k for the rest of the year.

I'm in the middle of doing my taxes. Before adding the 1099 income, I'm getting a ~$4.5k return, combined federal and CA. Once I add the 1099 income, I owe ~$8.5k, which is about a $13k swing, or 46% of my 1099 income. Am I missing something, or does this seem really high?